Image sensing apparatuses such as digital cameras and the like, which record and reproduce still images and moving images using a memory card having a solid-state memory element as a recording medium are already commercially available, and digital cameras having an auto white balance function are also commercially available.
With these digital cameras, a digital camera user can take an image regardless of the color temperature of a light source with which an object is irradiated. When a flash light is used to illuminate an object upon sensing an image, there are two different light sources, i.e., external light and flash light upon emitting flash light. At this time, the color temperatures of external light and flash light are independently detected. Then, white balance is determined from the influences of the color temperatures of external light and flash light based on the ratio of irradiation luminance.
Such conventional image sensing apparatus such as a digital camera or the like, holds a fixed value of the color temperature of the flash light as a designed value or stores a color temperature obtained by emitting the flash light upon individual adjustment of the image sensing apparatus at the time of production in a factory.
However, the color temperature of the flash light changes depending upon an emission amount, and repeated emission causes variation in the color temperature. As a result, the actual color temperature of the flash light varies for each emission of the flash light. If the actual color temperature largely differs from the stored fixed value or individual adjustment value, the color balance of a sensed image does not coincide with the actual color temperature.
Further, when the distance between the camera and object is long, since importance is attached to the color temperature of flash light even when the ratio of external light is large, a sensed image suffers inappropriate color balance.